In the area of automation for design and development of new products, Rapid Prototyping (RP) methods, also referred to as Desktop Manufacturing or Solid Freeform Fabrication (SFF) techniques, is a well known technique. RP methods produce a physical three-dimensional (3-D) model by representing the 3-D geometry of the part, depositing properly contoured material in two-dimensional (2-D) layers, and bonding each layer together. The 3-D geometry is collected by designing the part using a CAD system or imported from a 3-D scanner using Laser/optical vision or other technology. The collected 3-D geometry is converted into a triangular surface representation ideal for slicing the part into 2-D layers. A computer-controlled device acts on a material in a two-dimensional contour to create a current layer and the layer is assimilated with the previous layers, as described below, to produce a three-dimensional model or part.
There are numerous methods or techniques of Rapid Prototyping. Some of these techniques are Stereolithography, Solid Ground Curing, Laminated Object Manufacturing (LOM), Fused Deposition Modeling, Selective Laser Sintering (SLS), 3D Printing, Drop on Demand Jet, Ballistic Particle Manufacturing, Shape Deposition Manufacturing (SDM), and Scan Welding Deposition.
In Stereolithography, the free surface of a molten photo-polymer is selectively cured by a scanning ultraviolet (UV) light source. As the UV light source completes curing a layer, the light source is directed to create an adjacent layer which is bonded to the previous layer until a three-dimensional model is created.
In Laminated Object Manufacturing (LOM), blanks of plastic or paper sections are sliced out of sheet material by a laser beam. The slices of the sheets are bonded thermally to form a three-dimensional physical model.
In Selective Laser Sintering (SLS), thin layers of a polymer, ceramic or metal powder mixed with a bonding agent are locally sintered by a focused laser beam. The layers are built-up to form the three-dimensional physical model.
In 3D Printing and Drop on Demand Jet, a print head is used to form the three-dimensional object. In 3D Printing, thin layers of material powder are ejected from the print head with an adhesive binder to form the model. In Drop on Demand Jet, the printing head nozzle ejects droplets of a polymer and/or supporting wax, to deposit very thin layers of material.
In Scan Welding Deposition, metal layers are deposed in adjacent meandering beads by cold wire feeding in the molten puddle using plasma-arc or laser welding. The layers are welded on top of the previously laid sections until the three-dimensional model is formed.
Depending on the dimensional tolerance to the actual product and the RP method used, the completed prototype can be used for one or more purposes. These purposes include the visualization of the final part geometry and validation of its form, fit, and function. The model can in certain cases be used as a test model of the product, possibly at a convenient scale, in experimental evaluation of its performance properties (e.g. drag and lift coefficients in a wind tunnel).
The prototype sometimes can also be used as an indirect model for the development of permanent or single-use molds or dies, for production of the actual product by injection molding, evaporative pattern or investment casting, spray-metal tooling, room-temperature vulcanization (RTV) etc. These processes then duplicate the part shape, usually by a different material, in mass production.
One other purpose is to use the prototype directly as a real functional part, when the dimensional tolerances, surface finish, material structure and properties meet the part""s design specification. This is ideal for low-volume production of custom-made or one-of-a-kind products or replacement parts.
While current Rapid Prototyping (RP) methods answer several manufacturing and design needs, it has been recognized that these methods have several shortcomings. These shortcomings include that 1) parts can only be produced from a single uniform type of material, 2) the materials used are generally expensive and lack desired mechanical properties and 3) those models produced of metal generally lack both the strength and the required dimensional tolerances needed for direct tooling, die, and other real functional metal product applications.
This invention relates to a method and apparatus for producing a three-dimensional part from a plurality of planar layers. A sheet of planar material is placed on the partial part and ultrasonically welded, with the first sheet placed on a base. The sheet is cut to the shape of the partial part. The process of placing of the sheet materials on the partial, welding, and cutting of the two-dimensional contour layer is continued until part is complete.
In a preferred embodiment, the three-dimensional part has layers of different material. The materials can be layers of incompatible materials for ultrasonic welding in which voids are created through interposed non-compatible materials for ultrasonic welding, to allow ultrasonic welding of compatible material layers spaced by a sheet of incompatible material.
In a preferred embodiment a component, such as a thermal actuator; a optical component; an internal sensor; a plurality of electronic elements, or a mechanical actuator for creating a actively deformable part, is introduced between layers of material of the part. The method described allows the introduction of components which are sensitive to manufacturing temperatures. A pressure mask applies pressure to the top layer as the layer is ultrasonic welded to the part. In a preferred embodiment, the elongated sheets of material are carried on a supply drum and moved over the partial part using a feed system having the supply drum and a take-up drum.
The invention relates to a method and an apparatus to prototype cost effective parts with advanced and customized properties. These prototypes include full dense, full-strength metal and plastic functional parts; multiple-metal, multiple-plastic, and metal-plastic sandwich parts with internal pattern structures; composite materials with fiber reinforcements; active materials with embedded mechanical, thermal and optical fiber actuators; intelligent materials with encapsulated miniature sensors, electronics, processing and control elements; and with micro-hydraulic channels, fluidic networks, micro-mechanisms and mechacronics internal arrangements.
In a preferred embodiment, the three-dimensional geometry of a part is described as either a Stereolithography (STL) file or other standard CAD file format (IGES, DXF, etc.). This desired geometry is then sliced into a stack of 2-D section contours by software. In the subsequent hardware construction, each layer is produced out of thin sheet material. An ultrasonic welding device spot or seam welds the layer of material in place. After the welding of each layer or section has been completed, a high-speed cutter shapes the layer or section to the desired 2-D contour. Each remaining layer as well as possible embedded components, is deposited in the same manner until the entire part is complete.
In a preferred embodiment, the cutter is either a carbide or diamond tip scriber, or a rotary end-mill tool, but can also employ electrical discharge machining (EDM), abrasive water jet cutting (AWJC), laser, plasma-arc, ultrasonic or other cutting technology.
In a preferred embodiment, a control unit controls the movement of the ultrasonic welder and the cutter. In addition, the control unit also controls the positioning table, supporting the constructed three-dimensional part, the embedded component supply, as well as the material sheet feeder and removal mechanisms.
The apparatus and the method of the invention can bond dissimilar metals, polymers, or combinations, which allows prototypes of sandwiched materials to be produced. By bonding the material together at low temperatures instead of melting or heating as in conventional RP technologies, such as stereolithography, LOM, SLS, drop on demand and scan welding deposition, the absence of thermal expansion, shrinkage, and warping ensures the part""s dimensional accuracy. Because of the cold bonding of layers, the absence of material structure transformations preserves the original mechanical, thermal, electrical, etc. properties of its components and embedded elements. The weld arrangement when bonding the layers together can be designed to increase directionally the prototype strength, which allows the properties of the prototype to be customized or brought closer to the actual product (i.e., fully bonded sheet prototypes approach the strength of a solid part.)
In addition the method of the invention does not require special materials, thus reducing the cost of the prototypes. Most materials such as metals and polymers are available in low-cost thin sheet form. In addition the apparatus and the method of the invention is suitable for desktop manufacturing in a general environment, with no special air conditioning or other needs, due to the low energy requirements, voltage, emissions, noise, temperatures, etc. Thus hazards from radiation, electromagnetic fields and toxic fumes are avoided.
In a preferred embodiment, a three-dimensional part is made of filly dense metal, plastic or composite materials. In another preferred embodiment, embedded small components such as electronic circuitry, fiber optics, micro-sensors, actuators, processors and mechanisms can be located or developed in the three-dimensional part according to the method. This embodiment allows for prototypes with special internal structure and intelligence, designed to obtain customized micro-scale functionality.